1. Field of the Invention
The present invention generally relates to burner structures for use in portable heaters such as a high pressure oil burner provided with an oil discharge nozzle and air supply associated therewith to provide a combustible mixture which is ignited by a spark plug or a similar ignition device. More specifically, the invention relates to an ignition device for such burners in which an ignition spark is established over a nonconducting surface between a hot electrode and a grounded electrode or electrically conductor portion which enables a greater spark distance to be obtained as compared to an ignition spark which jumps across an air gap between two conducting electrodes. An additional feature of the present invention is the provision of a high limit control positioned proximal the burner such that flame resulting from heater inlet blockage will flash upstream into the vicinity of the high limit control to control operation of the burner.
2. Description of the Prior Art
Burners for use in a portable heater which utilize a spark plug type ignitor are well known with U.S. Pat. No. 4,081,238 issued Mar. 28, 1978 disclosing one such structure in which a conventional spark plug ignitor includes spaced electrodes defining an air gap through which a spark will jump to ignite a combustible mixture provided by an oil nozzle discharging a spray or mist of fuel oil associated with an air supply arrangement. Spark plugs and similar electrical spark ignition devices include spaced electrodes with one electrode being grounded and the other electrode connected to a high voltage energy source. When high voltage energy is supplied to the high voltage electrode, a spark characteristically jumps the air gap between the spaced tips of the two electrodes. The spark which jumps between the electrodes is located at a precise position in relation to a combustible mixture to obtain reliable ignition. In oil burners, the electrode spark is preferably located as far as possible from the oil spray with proper ignition relying upon "blowing" of the spark into the fringe of the oil spray. A spark can be "blown" a half inch or more by a moving air stream once the air between the electrodes has been ionized by the spark. More recent spark energy sources have been provided which replace a simple ignition transformer with an electronic system capable of providing increased high voltage energy sources and unique operating characteristics such as higher spark frequency thus providing the capability of improved ignition structures for oil burners and the like.
The above discussed prior art does not utilize an over surface spark device or ignition device for burners as disclosed in this application. Additionally, the prior art does not disclose a high limit control as disclosed in this application.